Metallic Rattle on Cold Start

When starting the car after it's been sitting overnight (especially when the air temps are below 40 degree) I notice a metallic knocking when I shift in to drive or reverse from park. The noise goes away when I shift back to Park or when the engine warms up / is running (after 3-5 mins of driving). The one constant I've noticed is that the noise is most noticeable between 800-1200 RPM.

Initially I thought this may be a loose heat shield, but after my local Honda dealer took a look, they said all heat shields are properly secured and they'd like me to leave it at the dealer overnight so they can replicate the sound in the morning.

Apparently they think it may be the timing chain tensioner, but they can't be sure. I've read online it may be the VTC actuator. Would either one of these be the likely culprit, or should they be looking elsewhere?